Think about it: polls track two types of voters, "registered" voters and "likely" voters. "Registered" means - well, that should be obvious. "Likely" means that you've voted in the last few presidential elections (I forget what the number is exactly, and some pollsters might do it slightly differently, I think). If you're a new voter this time around, chances are you're not registered yet, but that you're voting for Barack Obama. You won't show up in any of these polls because you are not "registered" or "likely," but you are indeed voting, and you're going O.
We of course don't know exactly how many people like this are out there. For that, we'll have to wait until November 4th. All I know is that, in one day thus far of volunteering at an Obama field office in a racially and ethnically hetereogeneous section of Philly, several people came in to register to vote. Obviously these people are brand-new voters, and judging by the fact that they were in our office, you'd assume they're voting for Obama (duh).
Here's what Rhodes Cook says over at Rasmussen Reports:
Since President George W. Bush's reelection in 2004, the Democrats have registered nearly 1.3 million additional voters while the Republicans have lost nearly 800,000. This, as states prepare to close their registration rolls in advance of the general election.
Not every one of the newly minted Democrats is a sure vote for Barack Obama next month. Some crossed over from the ranks of Republicans and independents solely to cast a primary ballot for Hillary Clinton. But many of the new Democrats registered long before the primaries or since then, creating a large pool of likely new voters for Obama. They comprise a necessary asset for the Democratic nominee in offsetting some powerful factors that could work against him.
Add to that the Obama campaign's vast resources, seemingly sound strategy and - at the moment - momentum and wind at their backs, and even I can find reason to remain (cautiously) optimistic about November.